Increasingly strict legal provisions relating to permitted pollutant emissions from motor vehicles containing internal combustion engines make it necessary to keep pollutant emissions as low as possible, at least within set operating areas of the internal combustion engine. This can be achieved firstly by reducing pollutant emissions generated during combustion of the air-fuel mixture in the respective cylinder of the internal combustion engine. Secondly, exhaust gas treatment systems are used in internal combustion engines to convert into harmless substances the pollutant emissions generated during the process of combustion of the air-gas mixture in the respective cylinders. Catalytic converters, which can convert carbon monoxide, hydrocarbons and nitrous oxides into harmless substances, are used for this purpose.
The prerequisite for a good long-term conversion capacity of catalytic converters is that the catalytic converters do not overheat. For this reason it is necessary for measures to be implemented where necessary to prevent the catalytic converter from overheating, particularly in operating areas of the internal combustion engine in which a very high output is expected to be generated by the internal combustion engine.
DE 10 2004 033 394 B3 discloses an engine control that sets an exhaust-gas temperature by influencing the air-fuel mixture and includes a temperature model which calculates the temperature for a component to be protected in the exhaust gas tract. The temperature model determines a predicted temperature for the component contained in the exhaust gas tract, said temperature becoming established after a fairly long time while maintaining current operating and driving conditions. The predicted temperature is the component temperature for the component to be protected that becomes established in continuous operation. In order for the component to be protected, the engine control system regulates the exhaust-gas as a function of the predicted temperature.